An integrated circuit (IC) device such as, for example, a die may be mounted on a package substrate to form an IC package assembly. A heat spreading element composed solely or primarily of a metal such as, for example, an integrated heat spreader and/or heat sink may be thermally coupled with the die to remove heat generated by the die when the die is in operation. For example, the heat may be generally conducted away from the die along a thermal pathway through the metal. Even when such heat spreading elements are composed of metals with high thermal conductivity such as, for example, copper, an in-plane temperature gradient may exist across the heat spreading element and reduce overall heat transfer effectiveness. For example, the gradient may result in a higher junction temperature (Tj) of the die or may require additional cooling power (e.g., higher fan power) to reduce the junction temperature.